Coating apparatus and method of forming coating layer using the same

ABSTRACT

A coating apparatus includes: a nozzle having a nozzle front end configured to spray a coating solution and a head configured to store the coating solution; a movement axis configured to cause the nozzle to move back and forth in a straight line; a rotating connection member configured to connect the movement axis with the nozzle and allow the nozzle to rotate; a stage disposed under the movement axis; and a cleaning means disposed at an end of the movement axis, and having a nozzle front end insertion unit in a concave shape of the nozzle front end and a base fixing the insertion unit, wherein the nozzle is fixed in a normal direction of a surface of the stage by the movement axis, moves back and forth in an extension direction of the movement axis, and rotates with respect to the movement axis.

This application claims the benefit of Korean Patent Application No.10-2010-0105626, filed on Oct. 27, 2010, which is hereby incorporated byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a coating apparatus used for aphotoresist (PR) or organic material coating process among liquidcrystal display (LCD) manufacturing processes, and more particularly, toa coating apparatus capable of managing a front end of a nozzle withoutpriming and a method of forming a coating layer using the coatingapparatus.

2. Discussion of the Related Art

In general, a process of manufacturing a liquid crystal display moduleemploying a thin film transistor (TFT) is divided into a TFT process, acell process, and a module process.

In the TFT process, a TFT is repeatedly formed in an array on a glasssubstrate. The TFT process includes a plasma enhanced chemical vapordeposition (PECVD) process of introducing a gas required for depositioninto a vacuum chamber, and transforming the introduced gas into plasmausing radio frequency (RF) power to perform deposition on the substratewhen pressure and substrate temperature are set, a sputtering process inwhich gaseous ions having high energy in plasma formed by RF power ordirect current (DC) power collide with a target surface, and atoms to bedeposited are sputtered from the target and deposited on the substrate,a photolithography process of selectively radiating light to a PR usinga mask having a desired pattern to form the same pattern as the maskpattern according to a principle that when a photosensitive chemical(e.g., PR) reacts with light, its properties are changed, and an etchingprocess using a phenomenon that a reactive material such as atoms orradicals produced from gas plasma reacts with the material deposited onthe substrate and is converted into a volatile material.

The cell process includes an alignment layer deposition process offorming alignment layers on a lower substrate on which a TFT is formedand an upper substrate on which a color filter is formed, a rubbingprocess of causing liquid crystals to be aligned on the alignment layer,a spacer process of dispensing spacers, and a liquid crystal injectionprocess of attaching the upper substrate and the lower substrate to eachother, injecting liquid crystals thereinto, and then sealing aninjection hole.

In the module process, a quality of a product finally provided to a useris determined In this process, a polarizing film is attached to acompleted panel, a driver integrated circuit (IC) is mounted, a printedcircuit board (PCB) is assembled, and finally a backlight unit and achassis are assembled.

In the photolithography process of the TFT process among these LCDmanufacturing processes, light is selectively radiated to a PR whichreacts with light to have a changed property through a mask having adesired pattern, thereby forming the same pattern as the mask pattern.

Such a photolithography process is carried out in order of a PR coatingoperation of coating a deposited thin film, that is, a glass surface,with a PR, an exposure operation of selectively radiating light using amask, and a development operation of removing the PR in an illuminatedportion using a developer to form a pattern.

Among coating apparatuses used for PR coating in the PR coatingoperation, a “spinless coater” includes, as shown in FIG. 1, a coaterchuck 10 for fixing a glass G, a nozzle 12 for spraying a PR solutionwhile moving over an upper surface of the glass G fixed by the coaterchuck 10, and a cleaning unit 20 for cleaning the nozzle 12.

As shown in FIG. 2, the cleaning unit 20 is in the form of one modulecomposed of a cleaner 22, a priming roller 24, and a standby unit 26,and is disposed on one side of the coater chuck 10.

Such a coating apparatus operates in a normal mode in which the nozzle12 repeatedly sprays a PR solution and an idling mode in which thenozzle 12 temporarily stops spraying the PR solution. Operations of thenozzle 12 according to the modes will be described below.

First, in the normal mode, a coating process in which the nozzle 12sprays a PR solution to the surface of the glass G to perform PRcoating, a cleaning process in which, after the coating operation forthe one glass G is finished, the nozzle 12 returns to the cleaning unit20 and is cleaned in the cleaner 22, and a preparation process in whichthe PR solution of the nozzle 12 is dispensed by the priming roller 24to enter a spray preparation state are performed in sequence. After thepreparation process, the coating process is repeated so that coatingoperations for a plurality of glasses are continuously carried out.

In the preparation process for the spray preparation state, the PR atthe front end of the nozzle 12 may be dried until the next glass isprepared after the one glass G is coated, and thus the PR solution isdispensed little by little. Such a PR dispensation also prevents acleaning solution from entering the nozzle 12 while cleaning isperformed by a mobile cleaner 23.

In the cleaning process, the mobile cleaner 23 installed at the cleaner22 moves and cleans the nozzle 12.

In the idling mode, after the nozzle 12 having finished the coatingprocess undergoes a cleaning process and a preparation process, it ismoved to the standby unit 26 and undergoes a standby process of beingdipped into a PR solution P contained in the standby unit 26. After apredetermined time, the cleaning process is performed again.

In other words, in the idling mode, the nozzle 12 is dipped into the PRsolution P during the standby process to prevent the PR solutionremaining in the nozzle 12 from being completely dried and to smoothlyperform a restarted coating process.

The dipping operation is performed by moving the nozzle 12 up and down.This is enabled because the nozzle 12 has an operation structure capableof moving up and down due to the characteristics of spinless coatingthat a PR dispensing operation should be precisely performed.

However, the conventional spinless coater including such a cleaning unithas some problems. The PR may be dried on the outside of the nozzle 12dipped in the idling mode and hinder a nozzle cleaning operation. Also,the PR solution P contained in the standby unit 26 may become hard andcause problems. Furthermore, it is difficult to maintain an appropriateamount of PR in the standby unit 26.

Lately, substrates have become larger and are damaged by even a smallimpact. To prevent such damage, substrates are floated and conveyed inthe air, and a method of performing each unit process with a substratefloated over a stage not to contact the stage surface is under research.For this reason, coating apparatuses require an air-floating stage, andare required to form a coating layer with a substrate floated in theair.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a spinless coatingapparatus and a method of forming a coating layer using the same thatsubstantially obviate one or more of the problems due to limitations anddisadvantages of the related art.

An advantage of the present invention is to provide a spinless coatingapparatus capable of preventing a nozzle from being polluted withoutpriming and maintaining the degree of precision in a Z-axis directionwith a substrate floated over a stage to prevent deterioration ofcoatability of a photoresist (PR), etc.

Additional features and advantages of the invention will be set forth inthe description which follows, and in part will be apparent from thedescription, or may be learned by practice of the invention. These andother advantages of the invention will be realized and attained by thestructure particularly pointed out in the written description and claimshereof as well as the appended drawings.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described, a coatingapparatus includes: a nozzle having a nozzle front end configured tospray a coating solution and a head configured to store the coatingsolution; a movement axis configured to cause the nozzle to move backand forth in a straight line; a rotating connection member configured toconnect the movement axis with the nozzle and allow the nozzle torotate; a stage disposed under the movement axis; and a cleaning meansdisposed at an end of the movement axis, and having a nozzle front endinsertion unit in a concave shape of the nozzle front end and a basefixing the insertion unit, wherein the nozzle is fixed in a normaldirection of a surface of the stage by the movement axis, moves back andforth in an extension direction of the movement axis, and rotates withrespect to the movement axis.

In another aspect, a method of forming a coating layer using a coatingapparatus including a nozzle having a nozzle front end configured tospray a coating solution and a head configured to store the coatingsolution, a movement axis configured to cause the nozzle to move backand forth in a straight line, a rotating connection member configured toconnect the movement axis with the nozzle and allow the nozzle torotate, a stage disposed under the movement axis, and a cleaning meansdisposed at an end of the movement axis and having a nozzle front endinsertion unit in a concave shape of the nozzle front end and a basefixing the insertion unit, wherein the nozzle is fixed in a normaldirection of a surface of the stage by the movement axis, moves back andforth in an extension direction of the movement axis, and rotates withrespect to the movement axis, includes: moving the nozzle front end tothe one end of the movement axis to dispose the nozzle front end to facethe nozzle front end insertion unit of the cleaning means; moving thenozzle front end insertion unit up to closely adhere the nozzle frontend insertion unit close to the nozzle front end; moving the nozzlefront end along the movement axis to clean the nozzle front end;floating a substrate in the air to mount the substrate over the stage tobe spaced apart from the stage by a predetermined distance; rotating thecleaned nozzle front end to be aligned with one end of the substratemounted over the stage; a dwelling operation of pre-dispensing a coatingsolution at the nozzle front end to fill a gap between the nozzle frontend and the substrate with the coating solution; and spraying thecoating solution while moving the nozzle front end along the movementaxis at a predetermined speed to form a coating layer on the substrate.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a plan view schematically showing a nozzle cleaning unit of aspinless coater and a coating process using a nozzle according to aconventional art;

FIG. 2 is a schematic cross-sectional view of the nozzle cleaning unitemployed in the conventional spinless coater;

FIG. 3 is a perspective view of a spinless coating apparatus accordingto an exemplary embodiment of the present invention;

FIGS. 4A to 4C are views illustrating a process of forming a coatinglayer on a substrate using the coating apparatus according to anexemplary embodiment of the present invention; and

FIG. 5 is a view illustrating a dwelling operation in the process offorming the coating layer using the coating apparatus according to anexemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Reference will now be made in detail to embodiments of the presentinvention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, similar reference numbers will be used torefer to the same or similar parts.

FIG. 3 is a perspective view of a spinless coating apparatus accordingto an exemplary embodiment of the present invention.

As shown in the drawing, a spinless coating apparatus 100 according toan exemplary embodiment of the present invention includes a nozzle 125configured to spray a coating solution, a movement axis 110 configuredto cause the nozzle 125 to move in a straight line and fix the nozzle125 in a Z-axis direction, a rotating connection member 112 configuredto connect the nozzle 125 with the movement axis 110 and rotate thenozzle 125, a stage 140 over which a substrate is mounted and floated,and a cleaning means 162 for cleaning a nozzle front end 122.

The nozzle 125 configured to spray the coating solution to the substrateis made of a metal, and includes the nozzle front end 122 from which thecoating solution is sprayed and a nozzle head 120 configured to supplythe coating solution to the nozzle front end 122. As the nozzle frontend 122, a bar as long as a substrate width is fixed at a predetermineddistance from the substrate 190, and has a pentagonal cross-sectionwhose tips are pointed.

Meanwhile, the nozzle head 120 is supplied with the coating solutionfrom the outside, stores the coating solution, and supplies anappropriate amount of the stored coating solution to the nozzle frontend 122.

Also, the nozzle head 120 is fixed to the movement axis 110 extending inone direction by the rotating connection member 112. Due to such astructure, the nozzle front end 122 is stably fixed in the Z-axisdirection, that is, a normal direction of the stage 140. Here, thenozzle head 120 is fixed to the movement axis 110 and can be rotatedfrom 90 degrees to 360 degrees by the rotating connection member 112.

The reason that the nozzle 125 is fixed to the movement axis 110 not tomove in the Z-axis direction is for process stability. A substrate 190floated in the air over the stage 140 actually has a slight error inheight from a surface of the stage 140 due to air floatation. When thenozzle 125 moves also in the Z-axis direction in this situation, aheight error range increases, and coating stability deteriorates.

If the nozzle 125 can move in the Z-axis direction, vertical motion iscontinuously performed. The repeated vertical motion may deteriorateheight reproducibility in the Z-axis. In this case, the function ofmanaging the nozzle front end 122 remarkably deteriorates, which mayincrease coating process defects. To prevent this problem, the nozzle125 of the coating apparatus 100 according to an exemplary embodiment ofthe present invention is fixed and does not move in the Z-axisdirection.

The stage 140 is connected with a substrate transfer path (not shown),which is a transfer path of the substrate 190, so that the substrate 190is floated and moved in the air to be mounted over the stage 140 at apredetermined distance, or has a loader (not shown) and an unloader (notshown) so that the substrate 190 is mounted on the stage 140.

Lately, the substrates 190 have become larger, and substrate transferpaths (not shown) have been prepared to minimize damage caused bycontact with another component when the substrate 190 is moved. Thecoating apparatus 100 according to an exemplary embodiment of thepresent invention also has a plurality of holes (not shown) configuredto discharge air having appropriate pressure to float the substrate 190in parallel with the surface of the stage 140 at a predetermined heightover the surface of the stage 140 according to such an air-floatingtransfer scheme.

Due to such a structure, the large-area substrate 190 can be floated inthe air and continuously moved to the stage 140 through the substratetransfer path (not shown).

Meanwhile, the most remarkable characteristic of the coating apparatus100 according to an exemplary embodiment of the present invention is thecleaning means 162 prepared at one end of the movement axis 110 at whichthe nozzle head 120 is fixed. The cleaning means 162 has a nozzle frontend insertion unit 160 having a groove hm in a concave shape of thenozzle front end 122 so that the nozzle front end 122 can be inserted.The cleaning means 162 has a base 150 configured to maintain the nozzlefront end insertion unit 160 fixed even when the nozzle front endinsertion unit 160 rubs against the nozzle front end 122, and a verticaldrive means 153 for vertically (i.e., in the Z-axis direction) movingthe nozzle front end insertion unit 160 on the base 150.

The nozzle front end insertion unit 160 is made of a material havingexcellent elasticity and an excellent characteristic for removing acoating solution on a surface of the nozzle front end 122, for example,rubber or high-elastic sponge.

The reason that vertical drive means 153 is prepared in the cleaningmeans 162 to vertically move the nozzle front end insertion unit 160 isthat the nozzle front end 122 and the nozzle head 120 need to be fixedin the vertical direction, that is, the Z-axis direction, due to thecharacteristics of the coating apparatus 100 according to an exemplaryembodiment of the present invention, and the nozzle front end insertionunit 160 needs to be closely adhered to the nozzle front end 122 due tothe characteristics of the cleaning means 162 according to an exemplaryembodiment of the present invention.

A method of forming a coating layer on a substrate using the coatingapparatus having the above-described constitution according to anexemplary embodiment of the present invention will be described below.

FIGS. 4A to 4C are views illustrating a process of forming a coatinglayer on a substrate using the coating apparatus 100 according to anexemplary embodiment of the present invention.

First, as shown in FIG. 4A, the nozzle head 120 and the nozzle front end122 are moved to one end of the movement axis 110 at which the cleaningmeans 162 is present. At this time, a length direction of the nozzlefront end insertion unit 160 of the cleaning means 162 is disposed inthe same direction as the movement axis 110, and thus a long axis of thenozzle front end 122 is disposed in parallel with the movement axis 110.

Thereafter, when the nozzle front end 122 is disposed to face the nozzlefront end insertion unit 160 of the cleaning means 162, the nozzle frontend insertion unit 160 is moved up by the vertical drive means 153 to beclosely adhered to the nozzle front end 122 with no space therebetween.

Subsequently, while the nozzle front end insertion unit 160 and thenozzle front end 122 are closely adhered to each other, the nozzle frontend 122 and the nozzle head 120 are slowly moved along the movement axis110 to remove a coating solution on the nozzle front end 122. When thenozzle front end 122 slowly moves in the nozzle front end insertion unit160, the coating solution on the nozzle front end 122 is transferred tothe nozzle front end insertion unit 160. This is because the coatingsolution has higher adhesion to the nozzle front end insertion unit 160made of rubber, high-elastic sponge, etc. than the metallic nozzle frontend 122, and there is another force such as a frictional force.

For this reason, the coating solution on the nozzle front end 122 iscompletely removed.

In comparison with conventional priming and a cleaning method of dippinga nozzle front end into a coating solution, the cleaning of the nozzlefront end 122 is performed within a short time and does not require acleaning solution, etc. Thus, the coating solution contained in thenozzle front end 122 is not polluted. Also, since the coating solutiondoes not remain on the surface of the nozzle front end 122, a failuresuch as a horizontal line defect does not occur during a coatingprocess.

When the cleaning of the nozzle front end 122 is finished, the nozzlefront end insertion unit 160 of the cleaning means 162 is moved down andfixed to the base 150. At this time, although not shown in the drawing,a cleaning solution, etc. is sprayed on the nozzle front end insertionunit 160 to remove the remaining coating solution transferred from thesurface of the nozzle front end 122 and make the nozzle front endinsertion unit 160 clean.

As shown in FIG. 4B, the cleaned nozzle front end 122 is moved along themovement axis 110 to a portion at which one end of the stage 140 isdisposed and rotates through 90 degrees so that a width of the end ofthe stage 140 is aligned with the long axis of the nozzle front end 122.

While the cleaning and movement of the nozzle front end 122 areperformed, the substrate 190 floated in the air is moved through asubstrate transfer path (not shown) and disposed over the stage 140. Atthis time, the stage 140 also discharges air through a plurality ofholes at a predetermined pressure so that the substrate 190 does notcome in contact with a surface of the stage 140. Thus, the substrate 190is floated in the air at a predetermined distance from the surface ofthe stage 140.

Since the substrate 190 does not come in contact with the surface of thestage 140 and is kept in a floated state in the air, it is possible toprevent scratches or damage caused by contact with the surface of thestage 140. Also, by preventing contact with a pollution source such asfine dust on the stage 140, it is possible to prevent pollution of thesubstrate 190 and introduction of a foreign substance, etc.

Subsequently, as shown in FIG. 4C, a pre-dispense process of spraying apredetermined amount of a coating solution 180 from the nozzle front end122 is performed with the nozzle front end 122 disposed at one end ofthe substrate 190 floated in the air over the stage 140, and a dwellingprocess of gradually spraying the predetermined amount of the coatingsolution 180 is continuously performed so that a gap between the nozzlefront end 122 and the substrate 190 is filled with an appropriate amountof the coating solution 180 as shown in FIG. 5 (a drawing illustrating adwelling process among operations of forming a coating layer using thecoating apparatus according to an exemplary embodiment of the presentinvention).

After this, the appropriate amount of the coating solution 180 iscontinuously sprayed through the nozzle front end 122 while the nozzlefront end 122 and the head 120 are moved along the movement axis 110 ata predetermined speed, thereby forming a coating layer 195 on thesubstrate 190. Here, the coating solution 180 may be a photosensitivematerial such as photoresist (PR), an alignment solution such aspolyimide, or an organic insulating material such as benzocyclobutene orphoto-acryl.

Subsequently, when the nozzle front end 122 arrives at the other end ofthe substrate 190, the spray of the coating solution 180 is stopped, andthe substrate 190 on which the coating layer 195 is formed is movedalong the substrate transfer path (not shown) with the distance betweenthe stage 140 and the substrate 190 floated in the air over the stage140 reduced. At this time, the nozzle front end 122 is rotated againthrough 90 degrees to be parallel with the movement axis 110, and movedto the one end of the movement axis 110 again to be disposed above thecleaning means 162.

Thereafter, the above-described operations are repeated to continuouslyform a coating layer on a new substrate.

When the process of forming the coating layer 195 on the substrate 190is performed using the spinless coating apparatus 100 according to anexemplary embodiment of the present invention as described above,priming does not need to be performed, and time for forming a coatinglayer per unit area is reduced because cleaning is simply performedusing the cleaning means having the nozzle front end insertion unit 160made of rubber, high-elastic sponge, etc.

Also, since the nozzle front end 122 and the head 120 are fixed to themovement axis 110 and moved back and forth in only one straight lineeven when the substrate 190 is floated in the air and mounted over thestage 140, the nozzle front end 122 is fixed in the Z-axis direction,that is, a normal direction of a stage surface. Thus, an error does notoccur in the Z-axis direction even when a coating process is repeated.Consequently, a conventional coating defect caused by an error in theZ-axis direction when the nozzle front end 122 is moved in the Z-axisdirection is prevented to obtain coating stability.

As described above, a spinless coating apparatus according to anexemplary embodiment of the present invention has a cleaning meanscapable of vertically (i.e., in a Z-axis direction) moving and made of aspecific material. Thus, a nozzle passes through the cleaning meansevery time before a substrate is coated with a PR, etc., and coatingwith the coating material is performed with a remaining PR completelyremoved from a nozzle surface, thereby preventing pollution of thenozzle, a protrusion generated due to a remaining material, and ahorizontal line defect.

Also, since the nozzle is fixed in the Z-axis direction and moves backand forth in only one direction, it is possible to prevent deteriorationof coatability resulting from deterioration of the degree of precisioncaused when the nozzle repeatedly moves in the Z-axis direction. Thus,it is possible to prevent a coating defect caused by a thicknessdifference of a PR, etc.

Further, since priming is omitted, coating time per unit area isreduced.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

1. A coating apparatus, comprising: a nozzle having a nozzle front endconfigured to spray a coating solution and a head configured to storethe coating solution; a movement axis configured to cause the nozzle tomove back and forth in a straight line; a rotating connection memberconfigured to connect the movement axis with the nozzle and allow thenozzle to rotate; a stage disposed under the movement axis; and acleaning means disposed at an end of the movement axis, and having anozzle front end insertion unit in a concave shape of the nozzle frontend and a base fixing the insertion unit, wherein the nozzle is fixed ina normal direction of a surface of the stage by the movement axis, movesback and forth in an extension direction of the movement axis, androtates with respect to the movement axis.
 2. The coating apparatus ofclaim 1, wherein the nozzle front end insertion unit is disposed to havea long axis in a direction parallel to the movement axis.
 3. The coatingapparatus of claim 1, wherein the cleaning means has a vertical drivemeans for vertically moving the nozzle front end insertion unit.
 4. Thecoating apparatus of claim 1, wherein the nozzle front end insertionunit is made of rubber or high-elastic sponge.
 5. A method of forming acoating layer using a coating apparatus comprising a nozzle having anozzle front end configured to spray a coating solution and a headconfigured to store the coating solution, a movement axis configured tocause the nozzle to move back and forth in a straight line, a rotatingconnection member configured to connect the movement axis with thenozzle and allow the nozzle to rotate, a stage disposed under themovement axis, and a cleaning means disposed at an end of the movementaxis and having a nozzle front end insertion unit in a concave shape ofthe nozzle front end and a base fixing the insertion unit, wherein thenozzle is fixed in a normal direction of a surface of the stage by themovement axis, moves back and forth in an extension direction of themovement axis, and rotates with respect to the movement axis, the methodcomprising: moving the nozzle front end to the one end of the movementaxis to dispose the nozzle front end to face the nozzle front endinsertion unit of the cleaning means; moving the nozzle front endinsertion unit up to closely adhere the nozzle front end insertion unitclose to the nozzle front end; moving the nozzle front end along themovement axis to clean the nozzle front end; floating a substrate in theair to mount the substrate over the stage to be spaced apart from thestage by a predetermined distance; rotating the cleaned nozzle front endto be aligned with one end of the substrate mounted over the stage; adwelling operation of pre-dispensing a coating solution at the nozzlefront end to fill a gap between the nozzle front end and the substratewith the coating solution; and spraying the coating solution whilemoving the nozzle front end along the movement axis at a predeterminedspeed to form a coating layer on the substrate.
 6. The method of claim5, wherein mounting the substrate over the stage includes aligning atransfer path of the substrate floated in the air with an end of thestage and moving the substrate floated in the air over the stage.
 7. Themethod of claim 5, wherein spraying the coating solution while movingthe nozzle front end along the movement axis to form the coating layeron the substrate is performed with the substrate floated in the air overthe stage.